3.6 - For Those Running Premium Fuel

[Livernois Motorsports]

Thanks for this. I don't even have a 3.6, just an interest in tuning... and no way that I know of to datalog my JL. I appreciate the time you've taken to explain everything.

it's no worries, I was referencing those who were saying we were full of it. But it was a good chance to post proof. 6* of knock with 93, and 8.5 with 87. that's 6* learned from using 87, plus 2.5 active on top of it if you're using 87.

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[Goosed]

Ensue the lambasting, but I am the original OP and traded my wrangler in for a sizeable profit. Picked up an EcoPoop 2.7L F150. So while I do, again I really do see a very size-able increase in MPG with premium 93 vs. 87 regular in this F150 (~25 with 93 vs. 21 with 87), the $.60/gal delta basically makes it a wash in terms of miles/money spent.

 

[Livernois Motorsports]

Ensue the lambasting, but I am the original OP and traded my wrangler in for a sizeable profit. Picked up an EcoPoop 2.7L F150. So while I do, again I really do see a very size-able increase in MPG with premium 93 vs. 87 regular in this F150 (~25 with 93 vs. 21 with 87), the $.60/gal delta basically makes it a wash in terms of miles/money spent.

Ford especially does since they will continue to add timing if it deems it can take it.

in the mid 90's, to even the early 2000's maybe this would be different, but modern engines absolutely will add power and efficiency with better fuel, and also help prevent damage.

The whole reason OEM's are pushing for E15 fuel is because they are pushing things past the limit of 87 octane, and all things being equal e15 87 controls knock better than e10 87 in the real world.

 

[TheRaven]

Just go ahead and datalog it, you will see. when I say all, I do mean all of them do it, maybe not audible, but it is pulling out timing. The number of gladiators, and wranglers we have had across our dyno is not insignificant, and they all do it. 2018, 2019, 2020, 2021. My rental units have done it on vacation.

As I explained in my previous post, I am not debating whether or not the JL 3.6l pulls timing. I'm saying that the fact that it does DOES NOT mean you need to run premium fuel. All modern vehicles are designed to do this so they can operate optimally with different fuel qualities, temperatures and humidity ranges. You'll see it happen regardless of fuel octane on any modern vehicle. The question of "should I pay extra for premium fuel in my _______" comes down to this - will I gain power and/or fuel mileage by doing so and not changing anything else? The answer is no, you are not going to gain MPGs or HP on an N/A engine that was designed to run on 87...i've proven it many times over.

Now I have no doubt that with one of your tunes and higher octane both performance and efficiency can be improved...but it won't be much.

Ensue the lambasting, but I am the original OP and traded my wrangler in for a sizeable profit. Picked up an EcoPoop 2.7L F150. So while I do, again I really do see a very size-able increase in MPG with premium 93 vs. 87 regular in this F150 (~25 with 93 vs. 21 with 87), the $.60/gal delta basically makes it a wash in terms of miles/money spent.

I wanted to give you some support on this one - FI engines are a whole different ballgame. They really all should be running the highest octane you can get, but people don't want to pay the premium for premium fuel (and I don't blame them - it's $0.70-1.00 per gallon here) so manufacturers cripple their engines to make them run on 87. That being the case, you can see some pretty amazing differences on some FI vehicles just by running 93 octane.

 

[JimmyZ]

Pretty awesome video from Chris. Explains in depth with some great animations. This should leave you all with no questions

Wow that was informative. I knew premium doesn't give you better gas mileage but I didn't know all the inner workings he explained. Good watch! Thanks for sharing

 

[Livernois Motorsports]

As I explained in my previous post, I am not debating whether or not the JL 3.6l pulls timing. I'm saying that the fact that it does DOES NOT mean you need to run premium fuel. All modern vehicles are designed to do this so they can operate optimally with different fuel qualities, temperatures and humidity ranges. You'll see it happen regardless of fuel octane on any modern vehicle. The question of "should I pay extra for premium fuel in my _______" comes down to this - will I gain power and/or fuel mileage by doing so and not changing anything else? The answer is no, you are not going to gain MPGs or HP on an N/A engine that was designed to run on 87...i've proven it many times over.

Now I have no doubt that with one of your tunes and higher octane both performance and efficiency can be improved...but it won't be much.



I wanted to give you some support on this one - FI engines are a whole different ballgame. They really all should be running the highest octane you can get, but people don't want to pay the premium for premium fuel (and I don't blame them - it's $0.70-1.00 per gallon here) so manufacturers cripple their engines to make them run on 87. That being the case, you can see some pretty amazing differences on some FI vehicles just by running 93 octane.

here is the flaw in your logic.

So, if you pull 8.5* of spark running 87, and only 6* on 93, you have 2.5* more degrees of spark, if you don't think that equals more power, I don't think you know how engines work. Now, eventually, the 6* will be 0* after it learns the long term back out of it, so if you don't think 8.5* of spark over what it had with 87 in the tank will make more power, you couldn't be more wrong.

More power will always net better efficiency as the load will go down. The increase timing also generates less heat in the engine, especially exhaust valves/catalyst, which helps prevent the aforementioned cat overtemp fueling. Again, if you don't think the engine using more fuel to control temps doesn't impact efficiency, I don't know how to help with that.

Also, remember, basically every engine nowadays is so high strung, they are all really optimized for CAFE and EPA regulations, and allowed to work on 87. They are NOT designed for 87, they are merely configured to allow the use of 87 without damage (although, I do believe we are going to see cracked pistons eventually crop up on the gen2 with age from sustained spark knock).

Did my personal MOAB benefit? yes, did every rental JL I have stop audibly knocking on vacation when I switched to 91+ also yes. have I been working with calibration/vehicles/builds long enough to know that knock retard decreases power and efficiency? absolutely.

 

[TheRaven]

here is the flaw in your logic.

So, if you pull 8.5* of spark running 87, and only 6* on 93, you have 2.5* more degrees of spark, if you don't think that equals more power, I don't think you know how engines work. Now, eventually, the 6* will be 0* after it learns the long term back out of it, so if you don't think 8.5* of spark over what it had with 87 in the tank will make more power, you couldn't be more wrong.

More power will always net better efficiency as the load will go down. The increase timing also generates less heat in the engine, especially exhaust valves/catalyst, which helps prevent the aforementioned cat overtemp fueling. Again, if you don't think the engine using more fuel to control temps doesn't impact efficiency, I don't know how to help with that.

Also, remember, basically every engine nowadays is so high strung, they are all really optimized for CAFE and EPA regulations, and allowed to work on 87. They are NOT designed for 87, they are merely configured to allow the use of 87 without damage (although, I do believe we are going to see cracked pistons eventually crop up on the gen2 with age from sustained spark knock).

Did my personal MOAB benefit? yes, did every rental JL I have stop audibly knocking on vacation when I switched to 91+ also yes. have I been working with calibration/vehicles/builds long enough to know that knock retard decreases power and efficiency? absolutely.

The flaw here is not in my logic, it's in what we're discussing. You keep harping on timing...we don't disagree on that. Again, EVERY VEHICLE PULLS TIMING NO MATTER THE OCTANE OF THE FUEL. And yes, it's going to pull more timing on lower octanes...that's how it's designed to work.

The flaw in YOUR logic is this - the efficiency and power loss from this is so minute that it barely even shows up on dyno runs, let alone 1/4 mile times or anything else. Again, this process happens when it's humid, or just really hot or cold. If the power or efficiency loss were that significant, we'd notice significant changes with the weather. But we don't. This is just like the long-debunked "DOHC is better because it's more complicated" argument. Unless we can realize real life gains, we're just spending more money for nothing.

I know you are trying to sell a product, so it's silly to continue this argument. My point was simply that the 3.6l JL does not NEED to run premium, and that you won't gain anything appreciable from the significant extra cost. I'm not here to argue the minutae of spark advance tech.

 

[Livernois Motorsports]

The flaw here is not in my logic, it's in what we're discussing. You keep harping on timing...we don't disagree on that. Again, EVERY VEHICLE PULLS TIMING NO MATTER THE OCTANE OF THE FUEL. And yes, it's going to pull more timing on lower octanes...that's how it's designed to work.

The flaw in YOUR logic is this - the efficiency and power loss from this is so minute that it barely even shows up on dyno runs, let alone 1/4 mile times or anything else. Again, this process happens when it's humid, or just really hot or cold. If the power or efficiency loss were that significant, we'd notice significant changes with the weather. But we don't. This is just like the long-debunked "DOHC is better because it's more complicated" argument. Unless we can realize real life gains, we're just spending more money for nothing.

I know you are trying to sell a product, so it's silly to continue this argument. My point was simply that the 3.6l JL does not NEED to run premium, and that you won't gain anything appreciable from the significant extra cost. I'm not here to argue the minute of spark advance tech.

Chrysler has an internal torque calculation based on spark, and it's pretty accurate. 2.5*, depending on where it is in the curve, can impact power from 1-4% typically. 8*, is about 7-32% again, depending on the timing it's starting at, and what that desired timing was VS MBT spark. Look at the logs, having 6* of retard, and being left with 6.5* means it was wanting 12.5*, you've cut the ignition timing in half essentially. a 50% reduction in spark advance is about a 25% loss in power at that point in the curve. We aren't talking small numbers here.

As for "every" vehicle pulling timing regardless of fuel. If you run a brand new Mustang GT with 93 fuel, completely stock, it actually is adding timing for almost the entire pull, and is not pulling timing vs the borderline knock table. We own a GEN1 pentastar challenger, and it for sure didn't knock when stock. in fairness though, it didn't knock stock with 87, but a GEN1 is a much lower compression engine, and is far less prone to spark knock. If you'd like, I am prepared with data, are you?

We test thousands of vehicles a year, and when they are running 93 octane fuel, the times we see knock on a stock calibration are exceptionally rare, and usually an indicator for poor quality fuel, or and additive like STABIL being used in the fuel. We drain, and fill with fresh, trust 93 and confirm. In the case of some vehicles, like a C6 ZO6 shipped to us from Iowa some years back, we have seen as much as 100hp come back just from changing fuel to good quality 93. on a stock 505hp vehicle, you're talking a 20% loss in power.

We own numerous JL's, plus have had a fair number here, not to mention JT's, and did all of this testing personally, saw the data, validated the data, and reverse validated the data before beginning development of product. A battery cycle, with 93 in the tank, netted about 12hp and 16tq more than we saw on 93 (we used this set of baselines for our numbers), while still pulling timing from the learned table, and a true 87 baseline run as about 5 and 5 lower than that. so 17hp and 21tq. Or around a 5% gain from running 93 with no knock, vs 87 with knock.

You also do see significant changes based on weather. If cold, Chrysler, and all manufacturers, add timing. Same with cold coolant temps. Hot removes timing under both conditions.

This is why peak efficiency is fall and spring. mid 60's with low humidity is about the best balance for efficiency. The colder air allows for more timing, to make more power (which is why race cars are quicker in colder air) but since it's more dense, it uses more fuel (there is also some increase in drag effects as well). In the summer, in extreme heat, it makes less power, also dropping efficiency.

This is why the EPA emissions drive cycle is 40F to 80F, and manufacturers are allowed to disable certain emissions and fuel saving features outside of this range. This range is this is the spot where the impact on efficiency is essentially a deadband. less than 1% variance. but exit this pocket, and that all changes.

Remember, us telling people that 93 has a benefit, even when stock, does us 0 good if it weren't true. So we have nothing to gain from this, but owners absolutely have something to gain long term, and short term on their Jeeps by doing so. No one is buying a tuner because of us telling people 93 is better on their stock Jeep.

 

[Rodeoflyer]

I know you are trying to sell a product, so it's silly to continue this argument.

Actually, anyone in the Livernois organization has little to actually gain by arguing here. They're huge and the Jeep category is probably .01% of their interest.

Listen to what they're saying.. it's factual.

You typically have to pay for the information they're providing here.

 

[LarryB]

I can tell the difference between Shell 93 and other top tier premium gas (Sunoco, BP, Conoco,...) with same octane rating. Shell 93 is the only thing that completely eliminates low RPM pinging in my 3.6 during the hot/humid mid-atlantic summer months. in winter, I can get away with 87 or 89. I don't really pay attention to mpg so dunno about that.

I live in Oil Country, where almost all of the other parents at kid’s soccer games work for oil companies. They love these discussions, as the margin of 93 dwarfs the margin of 87.

 

[LarryB]

If you see a difference then use premium.
Don't post about it on a forum, because well, you see.
Someone can find an article from someone that says blah blah blah premium does nothing when it says you can use 87.
Maybe it is because it is july and all the planets are lined up.

I would believe my own eyes and brain, and not listen to naysayers that read an article once.

As I posted before, I live in Oil Country, so our economy literally runs on oil. We love the chat about 93 gas, as it is much higher margin than 87. It might help to consider the source of literature. I am sure there are articles praising the benefits of smoking brought to you by Big Tobacco as well.

 

[EJWF11]

Chrysler has an internal torque calculation based on spark, and it's pretty accurate. 2.5*, depending on where it is in the curve, can impact power from 1-4% typically. 8*, is about 7-32% again, depending on the timing it's starting at, and what that desired timing was VS MBT spark. Look at the logs, having 6* of retard, and being left with 6.5* means it was wanting 12.5*, you've cut the ignition timing in half essentially. a 50% reduction in spark advance is about a 25% loss in power at that point in the curve. We aren't talking small numbers here.

As for "every" vehicle pulling timing regardless of fuel. If you run a brand new Mustang GT with 93 fuel, completely stock, it actually is adding timing for almost the entire pull, and is not pulling timing vs the borderline knock table. We own a GEN1 pentastar challenger, and it for sure didn't knock when stock. in fairness though, it didn't knock stock with 87, but a GEN1 is a much lower compression engine, and is far less prone to spark knock. If you'd like, I am prepared with data, are you?

We test thousands of vehicles a year, and when they are running 93 octane fuel, the times we see knock on a stock calibration are exceptionally rare, and usually an indicator for poor quality fuel, or and additive like STABIL being used in the fuel. We drain, and fill with fresh, trust 93 and confirm. In the case of some vehicles, like a C6 ZO6 shipped to us from Iowa some years back, we have seen as much as 100hp come back just from changing fuel to good quality 93. on a stock 505hp vehicle, you're talking a 20% loss in power.

We own numerous JL's, plus have had a fair number here, not to mention JT's, and did all of this testing personally, saw the data, validated the data, and reverse validated the data before beginning development of product. A battery cycle, with 93 in the tank, netted about 12hp and 16tq more than we saw on 93 (we used this set of baselines for our numbers), while still pulling timing from the learned table, and a true 87 baseline run as about 5 and 5 lower than that. so 17hp and 21tq. Or around a 5% gain from running 93 with no knock, vs 87 with knock.

You also do see significant changes based on weather. If cold, Chrysler, and all manufacturers, add timing. Same with cold coolant temps. Hot removes timing under both conditions.

This is why peak efficiency is fall and spring. mid 60's with low humidity is about the best balance for efficiency. The colder air allows for more timing, to make more power (which is why race cars are quicker in colder air) but since it's more dense, it uses more fuel (there is also some increase in drag effects as well). In the summer, in extreme heat, it makes less power, also dropping efficiency.

This is why the EPA emissions drive cycle is 40F to 80F, and manufacturers are allowed to disable certain emissions and fuel saving features outside of this range. This range is this is the spot where the impact on efficiency is essentially a deadband. less than 1% variance. but exit this pocket, and that all changes.

Remember, us telling people that 93 has a benefit, even when stock, does us 0 good if it weren't true. So we have nothing to gain from this, but owners absolutely have something to gain long term, and short term on their Jeeps by doing so. No one is buying a tuner because of us telling people 93 is better on their stock Jeep.

Yes, this makes engineering sense.

I offer the following, non-biased technical abstract to further explain the circumstance.

https://saemobilus.sae.org/content/2020-01-5117/

From a personal practical standpoint… my Honda CRV struggles/runs rough in hot weather when running 87. I give it 93, and she purrs just fine.

but dont overlook, this boils down to a function of system (engine) and fuel formulation. I pump shell.

 

[TheRaven]

Remember, us telling people that 93 has a benefit, even when stock, does us 0 good if it weren't true. So we have nothing to gain from this, but owners absolutely have something to gain long term, and short term on their Jeeps by doing so. No one is buying a tuner because of us telling people 93 is better on their stock Jeep.

You say you are prepared with data - ok then, show me REAL WORLD results. Show me a dyno graph, 1/4 mile times, fuel logs, SOMETHING that proves that running premium actually does offer significant real world gains. Your degrees and percentages are all relevant to "normal" and as a result, very deceiving. Going from 1 to 2 is a 100% increase, but on a scale of 100, it's a change that won't even be noticed. So "put up or shut up" as they say - lets see the goods.

Again, i've been through this countless times with countless vehicles, and i've never seen real world gains in performance or fuel mileage from running premium over regular, JL included. I just got my Tahoe tuned this spring, and I gained 1.5mpg and smoother shifts...MAYBE a tiny bit of power but it's really tough to call. That's on premium with a tune. Given, the Tahoe and JL are different vehicles but the limitation is still the N/A motor. You just aren't going to gain much without FI or other modifications to get more air and fuel into the motor, and you sure as hell aren't going to gain just by changing fuel grades.

Actually, anyone in the Livernois organization has little to actually gain by arguing here. They're huge and the Jeep category is probably .01% of their interest.

What? They have a ton to gain/lose. Tuning business is 100% reputation. People don't hand over the computers from their $50k vehicles if they aren't confident you know what you're doing.

 

[Rodeoflyer]

What? They have a ton to gain/lose. Tuning business is 100% reputation. People don't hand over the computers from their $50k vehicles if they aren't confident you know what you're doing.

Livernois has been around in the tuning game as long as me and I'm 52 years old . Just so you know I've owned a shitload of mustangs and they know they're doing, probably more so than any tuner in the country.

When they speak you listen.. especially if it's free.

But I get it.. you want data.. I'm sure they have it.

 

[TheRaven]

Livernois has been around in the tuning game as long as me and I'm 52 years old . Just so you know I've owned a shitload of mustangs and they know they're doing, probably more so than any tuner in the country.

When they speak you listen.. especially if it's free.

But I get it.. you want data.. I'm sure they have it.

OH I know all about Livernois from my LS1 days. Being around for a long time doesn't make anyone immune from being wrong. After all, they've been wrong before.

But this is why I said I was so surprised. They should know better than to spread misinformation like this.

I will await some proof of their claims. If they can provide it they'll be the first in history to do so.

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